The present invention relates to a semiconductor device and, more particularly, to a semiconductor device in which a semiconductor element is mounted on a base having external terminals.
A BGA package has been widely used, since it is appropriate for a higher pin count package, and its inductance and noise is small because its power and ground is planar. However, with an increase in speed of operation frequency of the semiconductor device, electrical noise is increasing in ground even if the BGA package is used.
As a semiconductor device for reducing the electric noise, there is a well-known example in which multiple through holes are provided in a ground pattern as disclosed in JP-A-7-153869.
While the above known example discloses a structure to reduce ground inductance due to noise by providing multiple through holes on the ground, the noise can not be reduced sufficiently when operation becomes faster.
The inductance can be reduced by increasing the proportion of the number of power through holes and ground through holes relative to the number of signal through holes. In the through hole layout structure, the proportion of the number of the power through holes and ground through holes relative to the number of signal through holes has an significant effect on the number of total pins. If the number of the power and ground through holes per one signal through hole is large, the inductance is significantly reduced. However, manufacturing costs for the semiconductor device will be raised. If the number of the power and ground through holes per one signal through hole is small, then the inductance is not so reduced, although its production costs are decreased.
Therefore, just the provision of multiple ground through holes results in an enlarged and complicated package, even if high-speed operation is achieved.
Accordingly, it is an object of the present invention to provide a compact semiconductor device capable of suppressing an increase in noise to perform high-speed transmission.